The present invention relates to rotating machinery systems such as screw-type compressors, superchargers, and hermetically sealed refrigerant compressors where the drive motor is located on the suction side of the compressors. More specifically, the present invention is directed to unequally proportioned fluid passages that run axially along the motor to cool the motor in a way that provides a compact package. These passages are sized to transport lubricant expelled from a unique motor bearing oiling scheme along with the main fluid to complete the lubrication system.
Size and weight reduction of a screw compressor is highly desirable but problematic to achieve because of the need to both lubricate and cool the drive motor which generates heat that must be dissipated to ensure continued and reliable motor operation. One way of generating high motor power in a small package is to spin the motor at a very high speed, where lubrication of the motor bearings is critical. An object of my invention is a provide a way of porting lubricant to the motor bearings to lubricate and cool the bearings by flowing the lubricant through the bearing and expelling it into the main fluid flow where it is transferred to the compressor through the main fluid passages while entrained in the main fluid.
Another object of my invention is to achieve a compact screw compressor package wherein the motor directly drives one of the compressor screws in a two-screw compressor. Direct drive positions the motor on the same centerline as the driven compressor screw. The second compressor screw in a two-screw compressor meshes with the first screw, and is therefore positioned parallel to and aligned with the first screw, as shown in FIG. 2 described below. This creates an offset between the screw housing and motor housing as can be seen in FIG. 3. The main fluid passages in my invention are positioned to occupy this offset area on the suction side of the compressor where the motor resides, containing the overall cross section of the compressor/motor assembly in a minimized package size. The main fluid passages are sized to provide mist-flow velocities to carry the bearing lubricant entrained in the main fluid, while having sufficient surface area to cool the drive motor.
Before proceeding, it should be noted that the term “passage” and “opening” as used herein should be interpreted as essentially any structural element that is able to direct fluid between first and second points.